Before CAPD can be accepted as an established treatment for end-stage renal failure the long-term metabolic effects of the treatment have to be evaluated. Among factors of importance are the effects of the constant glucose supply and the continuous loss of amino acids and protein by the peritoneal route on lipid, carbohydrate and protein metabolism. The aim of the proposed investigations is to study on a prospective basis potentially deleterious, as well as salutary metabolic effects of CAPD. Patients with end-stage renal failure will be studied before start of CAPD, after 2-4 months of CAPD and thereafter at intervals of 6-l2 months over a period of 3 years. In addition to routine clinical and biochemical survey the following studies will be performed: thorough nutritional surveys; nitrogen balances on a defined diet individualized for each patient with regard to protein and energy intake to mimic the patients spontaneous nutritional intake at home; plasma and muscle free amino acids and plasma proteins; losses of proteins and amino acids in the dialysate; glucose uptake from diealysate; clearance of urea, creatinine, and endogenous middle molecules; oral glucose tolerance tests with determinations of insulin and glucagon in serum; studies of lipid metabolism by determanition of serum lipids and lipoprotein patterns, composition and metabolism of adipose tissue, and turnover rate of exogenous i.v. triglycerides; determination of glycogen and electrolytes in muscle tissue; total K+ estimated by 40K - determination in a total body counter. The possibility to replace glucose by amino acids as osmotic agent will be explored in dwell experiments with determinations of amino acids in plasma and dialysate and rates of ultrafiltration. On basis of data obtained, dialysis solutions for CAPD with altered composition will be prepared and clinically tested.